DancingOmelette: I can't speak for ATI, although I'm sure this is possible with catalyst,
Ezzthetic: You can in fact do this easliy in Catalyst, if your wide-screen monitor doesn't have a 4:3 option.
Just select Enable GPU Scaling, then Maintain Aspect Ratio. Then if you select one of the 4:3 resolutions in the game set up, you will get the game in the proper ratio.
Of course, you should also apply the registry hack mentioned elsewhere to get rid of the top and bottom bars.
Ezzthetic where did you find this registry hack? Here on the gog.com forums?
Edit: I found them. I tried it myself and it works for me. Here they are:
For those who are interested, there is a dude who recently discovered how to remove those eternal and useless horizontal black bars at least during the gameplay :D . This is not absolutely perfect but it just can't be better anyway ^_^ .
Procedure:
1-Start Regedit (as an administrator; it is actually a very vulnerable and fundamental zone of your OS).
{Open "Start Menu, All Programs, Accessories, Run" then enter regedit in the "open" textbox and click OK.}
2-Then, in the left side of the window, you have to search for the Registry Key "folder" HKEY_CURRENT_USER\Software\Ubisoft\Beyond Good & Evil\SettingsApplication.INI\Basic video. By selecting "Basic video", around twenty "values" almost all in a "Dual Word" format (DWORD).
3-So you'll have to create another one (for safety) also in "DWORD" format that you MUST name exactly "NoBands". (Of course without quotes. <_< )
{To create it, right-click anywhere around the other values and select "New, DWORD (32 bit) Value then name it NoBands.}
4-Finally, the only remaining step is to SET the "NoBands" value to 1 and close Regedit. Enjoy
Remember that this works (usually) only while you play, the bars should reappear during cinematics.